So I have been having some issues with importing .fbx files that where exported out of blender. This is an issue specific to blender I do not have these issues from any other modelling packages. Any .fbx imported that was created in blender that you tell to generate light maps using UE4’s auto light map generation come out with overlapping UV’s and strange distortions.
When attempting to toggle on/off generation of lightmaps from these assets there is often issues, and sometimes the .fbx needs to be imported again, with a completely new, clean import to get the light maps to stop or start auto generating.
I have tried to look into specific blender export settings, I am exporting with the bare minimum that I am aware of but I could have missed some settings.
Also seems that importing a blender export into max and then out from 3dsMax has the same issue, recreating the same mesh in 3ds max and exporting has no issues. even if the asset is vertex for vertex the same. Something from blender is causing this and I wanted to see if there are any other blender users that know of this issue and how you get around the problem.
This should show the issue, Asset was recreated in 3DS Max with no issues. This is not fixed by importing the fbx into 3ds max and then re-exporting. Something is saving to the .fbx when exported.
I always generate the lightmap UV in blender, so I never have had any similar issues until I baked a model I forgot to do this for.
I don’t think it’s “strange” per-se. The algorithm that creates the UVs expects to see a good FBX file that blender cannot produce.
Remember that the exporter is essentially a community made hack - It has been getting patched a little better over time, but it’s very far from providing the same quality that using a direct Maya export would produce.
To avoid the issue altogether just smart uv project a new UV to use as the lightmap. I usually use a .02 island size or greater. If the model is very intensive - like grass for instance, I’ll go down to .001 even, to get more area coverage (obviously that doesn’t matter since I never actually set shadows on vertex grass, but that’s besides the point).
As far as “resolving” the problem of the model export and automation.
You can try selecting the item, adding the edge cut modifier set to “sharp” edges and exporting the FBX with edges to see if that makes a difference. IT should - I’d still rather make the UV map manually in blender.
